U.S. patent number 6,960,188 [Application Number 09/999,493] was granted by the patent office on 2005-11-01 for catheter having enhanced distal pushability.
This patent grant is currently assigned to Abbott Laboratories Vascular Entities Limited. Invention is credited to Ib Erling Jorgensen.
United States Patent |
6,960,188 |
Jorgensen |
November 1, 2005 |
Catheter having enhanced distal pushability
Abstract
Apparatus for enhancing pushability and minimizing kinking of a
balloon catheter is provided, wherein a catheter comprises inner
and outer tubes, and a balloon that is proximally affixed to the
outer tube and distally affixed to the inner tube. The outer tube
extends distal to the proximal affixation point and at least
partially into the balloon segment to provide additional stiffness
and pushability. The outer tube may taper and connect to the inner
tube or to radiopaque markers disposed thereon. The outer tube
further may be selectively reinforced, as by using multipart
construction or using different tube textures, to selectively
provide added stiffness in areas susceptible to kinking.
Inventors: |
Jorgensen; Ib Erling
(Haigerloch, DE) |
Assignee: |
Abbott Laboratories Vascular
Entities Limited (Galway, IE)
|
Family
ID: |
25546401 |
Appl.
No.: |
09/999,493 |
Filed: |
November 30, 2001 |
Current U.S.
Class: |
604/103.09;
604/96.01; 606/192 |
Current CPC
Class: |
A61M
25/1006 (20130101) |
Current International
Class: |
A61M
25/10 (20060101); A61M 029/00 () |
Field of
Search: |
;604/96.01,523-526,103.09,102.02 ;606/194,195,191,192 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lucchesi; Nicholas D.
Assistant Examiner: DeSanto; Matthew F.
Attorney, Agent or Firm: Pisano, Esq.; Nicola A. Luce,
Forward, Hamilton & Scripps LLP
Claims
What is claimed is:
1. Apparatus suitable for enhancing pushability of a balloon
catheter, the apparatus comprising: an outer tube having proximal
and distal ends; an inner tube having proximal and distal ends and
a guidewire lumen extending therethrough, the inner tube disposed
coaxially within the outer tube to define an inflation lumen
therebetween; and a balloon having proximal and distal ends,
wherein the proximal end of the balloon is affixed to the outer
tube at a proximal affixation point and the distal end of the
balloon is affixed to the inner tube at a distal affixation point
to define a balloon segment extending therebetween, wherein the
outer tube tapers just distal to the proximal affixation point to a
reduced diameter segment, and the reduced diameter segment is
affixed to the inner tube at the proximal end and extends at least
one-half of the length of the balloon segment to increase
pushability of the balloon, but does not extend to the distal
affixation point, a tapered portion the outer tube just distal of
the proximal affixation point defining an inflation aperture
proximal of the distal end of the outer tube.
2. The apparatus of claim 1 wherein the outer tube comprises a
plurality of different materials at selected locations along its
length to selectively influence stiffness.
3. The apparatus of claim 2 wherein the outer tube comprises a
polymeric material.
4. The apparatus of claim 3 wherein the outer tube comprises
stainless steel.
5. The apparatus of claim 1 wherein sections of the outer tube
include a helical coil that enhances stiffness of the outer
tube.
6. The apparatus of claim 5 wherein a pitch of the helical coil
varies along a length of the outer tube.
7. The apparatus of claim 1 wherein the reduced diameter segment of
the outer tube and the inner tube to form a single reinforced
tube.
8. The apparatus of claim 1 further comprising at least one
radiopaque marker affixed to the inner tube and disposed within the
balloon segment.
9. The apparatus of claim 1 wherein sections of the outer tube
include braiding that vary the stiffness of the outer tube.
10. The apparatus of claim 1 wherein the outer tube is manufactured
using a single-wall material.
11. The apparatus of claim 1 wherein the outer tube is provided as
co-extruded tubing having different properties on inner and outer
sides of the tubing.
12. The apparatus of claim 1 wherein the inner and outer tubes are
at least partially affixed to each other at selected locations.
Description
FIELD OF THE INVENTION
The present invention relates to a surgical catheter, and more
particularly, a balloon catheter having a reinforced distal segment
to facilitate catheter pushability and minimize kinking.
BACKGROUND OF THE INVENTION
Angioplasty and stenting are widely used techniques for treating
vascular disease. In balloon angioplasty, a catheter having an
inflatable balloon affixed to its distal end is guided through a
patient's vasculature with the balloon in a deflated state, and the
balloon is positioned within a vascular lesion. The balloon then is
inflated to compress the atherosclerotic plaque against the vessel
wall to restore adequate blood flow in the vessel. Stenting
involves the deployment of small tubular prostheses, either balloon
expanded or self-expanding, that radially expand to maintain vessel
patency, and are commonly used in conjunction with balloon
angioplasty.
One problem associated with the use of balloon catheters is that
kinks may develop along the catheter. Because the catheter must be
relatively flexible to be advanced through tortuous vasculature, a
flexible catheter is prone to kink when pushed from its proximal
end by the physician. This is especially so when the distal end
encounters resistance from a tight stenosis. The term "pushability"
describes the ability of a catheter to transmit longitudinal forces
from the proximal to the distal end, without creating kinks, and
this is an integral characteristic of a successful catheter
design.
Previously-known balloon catheters have attempted to enhance
pushability primarily by reinforcing a proximal segment of the
catheter. U.S. Pat. No. 5,626,600 to Horzewski et al. (Horzewski)
describes a balloon dilatation catheter comprising proximal and
distal extremities, an inflation lumen extending therethrough, a
balloon disposed on the distal extremity that communicates with the
inflation lumen, and a separate guidewire lumen. A small plug may
be disposed within the guidewire lumen to separate the guidewire
lumen into a proximal stiffening section and distal guidewire
section. A stiffening mandrel may be inserted into the proximal
stiffening section of the guidewire lumen, proximal to the plug, to
influence proximal stiffness and to enhance pushability of the
catheter. According to the patent, the apparatus strives to enhance
catheter pushability by proving a catheter having "a stiff proximal
portion, a soft distal portion and a very soft low profile tip
portion."
One drawback associated with the catheter described in the
Horzewski patent is the potential for kinks to develop at the
distal end of the catheter, i.e., near the balloon. The stiff
proximal section may be readily advanced, but the location where
the soft distal portion joins the stiff proximal section may be
particularly susceptible to kinking. This adverse event is
especially likely to occur when the very soft distal section is
attempted to be pushed through a tight stenosis because there is no
distal reinforcement.
Furthermore, the distal end of the above-described balloon catheter
would be particularly susceptible to kink when used during a
stenting procedure. This is because mounting a stent over the
balloon increases the rigidity of the soft distal section, and the
joint between the soft and rigid segments is susceptible to kink
when the catheter is pushed forcefully.
Other catheter designs have provided an outer tube that extends
through the balloon segment to the distalmost end of the catheter.
U.S. Pat. No. 5,085,636 to Burns (Burns) describes a catheter
comprising an elongated flexible tube having an inflatable balloon
at its distal end. There is one single lumen for both the guidewire
and inflation/deflation functions, as a pair of distal valves
provide a fluid tight seal around the guidewire during inflation
and deflation of the balloon. The patent suggests that the
elongated flexible tube that extends to the distalmost end of the
catheter may be of an integral or multipart construction.
The Burns patent specifically recommends manufacturing the proximal
section from "hypotube" (stainless steel hypodermic needle tube),
while the distal segment comprises a flexible polymer tube. Like
the Horzewski device, Burns strives to increase overall pushability
by providing a primarily reinforced proximal segment. However, like
the device described in the Horzewski patent, the flexible distal
end of the device in the Burns patent still will be susceptible to
kinking, when it encounters a tight stenosis. In particular,
kinking may occur at the proximal balloon connection because at
this location a flexible polymer tube section is disposed between
the stiff hypotube section and the relatively stiff balloon
section.
In view of these drawbacks of previously known balloon catheters,
it would be desirable to provide apparatus that increases the push
force transmitted from the outer tube to the distal end of the
catheter, e.g., to facilitate pushability of the distal end through
a tight stenosis.
It still further would be desirable to provide apparatus having a
substantially continuous stiffness transition between the outer
tube of a coaxial catheter and the stent section of the
catheter.
It still further would be desirable to provide apparatus that
minimizes the formation of kinks near the distal end of a balloon
catheter.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention
to provide apparatus that increases the push force transmitted from
the outer tube to the distal end of the catheter, e.g., to
facilitate pushability of the distal end through a tight
stenosis.
It is another object of the present invention to provide apparatus
having a substantially continuous stiffness transition between the
outer tube of a coaxial catheter and the balloon section of the
catheter.
It is another object of the present invention to provide apparatus
that minimizes the formation of kinks near the distal end of a
balloon catheter.
These and other objects of the present invention are accomplished
by providing apparatus suitable for enhancing distal pushability of
a balloon catheter. The apparatus preferably comprises a catheter
having an outer tube, an inner guidewire tube that extends
coaxially within the outer tube, and a balloon disposed near the
distal end of the catheter. The balloon is affixed at a proximal
affixation point to the outer tube, and affixed at a distal
affixation point to the inner tube. Unlike previously-known
catheter designs, the outer tube extends at least partially through
the balloon segment, i.e., distal to the proximal balloon
affixation point, and the outer tube may be reinforced to increase
stiffness and pushability along this segment of the catheter.
In a preferred embodiment, the outer tube gradually tapers just
distal to the proximal affixation point. The taper extends at least
partially through the balloon segment to a smaller diameter, such
that it does not substantially increase the overall distal profile
of the catheter. An inflation aperture is provided in the outer
tube at a location just distal to the proximal affixation
point.
The apparatus further preferably comprises at least one radiopaque
marker affixed to the inner tube and disposed within the balloon
segment. The distal end of the outer tube may be affixed to the
radiopaque marker to enhance stiffness within the balloon segment
and increase pushability of the catheter through a tight stenosis.
Alternatively, the outer tube may taper distal to the proximal
balloon affixation point and connect directly to the inner tube,
such that the outer tube and inner tube become a single reinforced
tube.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features of the invention, its nature and various
advantages will be more apparent from the accompanying drawings and
the following detailed description of the preferred embodiments, in
which:
FIG. 1 is an illustration of the distal end of a previously-known
coaxial catheter design;
FIGS. 2A-2C are a schematic of the distal end of a reinforced
catheter in accordance with the present invention, and a helical
stiffening coil having constant and varying pitches,
respectively;
FIGS. 3A-3C describe an alternative embodiment of the present
invention having a separate connecting tube, and means for affixing
the connecting tube to the outer tube using a butt-weld and
lap-weld, respectively; and
FIG. 4 describes an alternative embodiment of the present invention
having an outer tube that tapers to connect to the inner guidewire
tube.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a previously-known balloon catheter from U.S.
Pat. No. 5,492,532 to Ryan et al. (Ryan) is described. Catheter 20
comprises outer tube 22, inner tube 24, and balloon 26 having
proximal and distal ends, the proximal end of balloon 26 being
affixed to outer tube 22 at proximal affixation point 27 and
distally affixed to inner tube 24 at point 29. Outer tube 22 and
inner tube 24 are provided in a coaxial alignment, such that
inflation lumen 23 communicates with balloon 26 while guidewire
lumen 25 allows catheter 20 to be advanced over a guidewire.
One drawback associated with this previously-known design is that
outer tube 22 terminates at proximal affixation point 27.
Consequently, the segment distal to outer tube 22 will be
susceptible to kinking when the distal end of catheter 20 is
advanced into a tight stenosis. The push force provided at the
proximal end of catheter 20 may not be fully transmitted to the
distalmost end of catheter 20, in part because outer tube 22
terminates at point 27.
The previously-known catheter design in FIG. 1 further is
susceptible to kinking when used in a stenting procedure. For
example, if a stent is mounted on balloon 26, it may span section
`S` and form a relatively rigid segment along this portion of
catheter 20. Because outer tube 22 also provides a relatively rigid
segment, the flexible segment `K` may be formed between outer tube
22 and proximal end of stent section `S` will be susceptible to
kinking when the distal end of catheter 20 encounters a tight
stenosis.
Referring to FIG. 2A, catheter 40 constructed in accordance with
principles of the present invention is described. Catheter 40
comprises proximal and distal ends, of which the distal end is
depicted in FIG. 2. The proximal end of catheter 40 communicates
with a traditional proximal hub assembly (not shown) that comprises
a proximal guidewire entry port and an inflation/deflation
port.
The distal end of catheter 40 comprises outer tube 42, inner tube
44 and balloon 46, each having proximal and distal ends. Inner tube
44 extends coaxially within outer tube 42 and extends beyond the
distal end of balloon 46. Inflation/deflation lumen 43 and
guidewire lumen 45 communicate with the proximal
inflation/deflation port and guidewire entry port, respectively.
Guidewire lumen 45 of inner tube 44 is configured to permit the
advancement of catheter 40 over guidewire 50.
The proximal end of balloon 46 is affixed to outer tube 42 at
proximal affixation point 47, e.g., using a solder, weld or
biocompatible adhesive, while the distal end of balloon 46 is
affixed to inner tube 44 at distal affixation point 53, as shown in
FIG. 2A. The area extending between proximal and distal affixation
points 47 and 53 defines balloon segment 55. The apparatus
preferably further comprises radiopaque markers 48 affixed to inner
tube 44 and disposed within balloon segment 55.
In accordance with principles of the present invention, outer tube
42 extends distally beyond proximal affixation point 47 to enhance
stiffness within balloon segment 55. Outer tube 42 preferably
comprises taper 49 that reduces the diameter of outer tube 42
within balloon segment 55 to reduce the overall distal profile.
Alternatively, taper 49 may be omitted and tube 42 may continue at
its original diameter throughout balloon segment 55.
In a preferred embodiment, outer tube 42 tapers inward just distal
to proximal affixation point 47, and the distal end of outer tube
42 is affixed to one or more radiopaque marker bands 48, as shown
in FIG. 2A. The reduced diameter distal section of tube 42 may
extend the entire length of balloon segment 55 and may be affixed
to inner tube 44 and the distal end of balloon 46 at distal
affixation point 53.
In the embodiment described in FIG. 2A, outer tube 42 comprises at
least one inflation aperture 52 disposed in a lateral surface at a
location distal to point 47 and proximal to the most proximal
radiopaque marker 48. Inflation aperture 52 permits fluid
communication between the proximal inflation/deflation port and
balloon 46 via lumen 43. In an alternative embodiment, outer tube
42 may terminate proximal to the most proximal radiopaque marker
within balloon segment 55, in which case the distalmost tip of tube
42 would communicate directly with balloon 48 via lumen 43.
The characteristics of outer tube 42 may vary along its length to
influence stiffness at selected locations, particularly to provide
increased stiffness along balloon segment 55. The characteristics
of outer tube 42 may be varied regionally by providing a rigid
section, braided or spiral-shaped section, or by providing bores or
slits at selected locations. FIGS. 2B and 2C illustrate embodiments
wherein helical coils 65 and 67, having constant and varying
pitches, respectively, may be used to selectively enhance stiffness
of outer tube 42. Helical coils 65 and 67 may enhance stiffness of
outer tube 42 proximal to or within balloon segment 55. Optionally,
outer tube 42 may be affixed to inner tube 44 at selected locations
along catheter 40, e.g., using a solder or weld, to enhance
stiffness and pushability so long as inflation lumen 43 is not
completely blocked.
Outer tube 42 may be manufactured using a single-wall tubing, or
may be provided as co-extruded tubing to allow for different
surface properties inside and outside the tubing. The
characteristics of catheter 40 further may be altered by
manufacturing outer tube 42 using at least one material along its
length, e.g., a combination of stainless steel and polymeric
materials using adhesives or advanced extrusion techniques. It
should be appreciated that providing different materials and/or
varying the textures of outer sheath 42 at any combination of
locations is intended to fall within the scope of the present
invention.
Referring to FIG. 3, an alternative embodiment of catheter 40 is
described wherein the distal end of outer tube 42 communicates with
a separate connecting tube 57 having proximal and distal ends.
Connecting tube 57 is disposed within balloon segment 55 and
preferably is affixed to at least one radiopaque marker 48, as
shown. The distal end of outer tube 42 may be affixed to the
proximal end of connecting tube 57, e.g., using biocompatible
adhesive. FIGS. 3B-3C, corresponding to inset 3 of FIG. 3A,
illustrate outer tube 42 being affixed to connecting tube 57 via
butt-weld 58 and lap-weld 60, respectively. Lap-weld 60 is
preferred to butt-weld 58 because lap-weld 60 may be less
susceptible to kink as push forces are transmitted from outer tube
42 to connecting tube 57. The embodiments described in FIG. 3
provide reinforced tube segments of differing characteristics
without having to manufacture one relatively complicated piece for
outer tube 42. Furthermore, connecting tube 57 prevents kinks from
developing between radiopaque markers 48, an otherwise common
location for the formation of kinks.
Referring to FIG. 4, an alternative embodiment of catheter 40 in
accordance with the present invention is described. Outer tube 42
is affixed to the proximal end of balloon 46 at proximal affixation
point 47, then tapers via taper 49 to connect to inner tube 44. In
this embodiment, outer tube 42 and inner tube 44 become a single,
reinforced tube 59 when connected. As described hereinabove, the
properties of outer tube 42 and reinforced tube 59 may be tailored
to provide varying stiffness at selected locations along the length
of catheter 40.
While preferred illustrative embodiments of the invention are
described above, it will be apparent to one skilled in the art that
various changes and modifications may be made therein without
departing from the invention. The appended claims are intended to
cover all such changes and modifications that fall within the true
spirit and scope of the invention.
* * * * *